Magnetic recording media

Abstract

The running properties and durability under a wide range of temperature and humidity conditions are improved by the presence of terminally modified polyhexafluoropropylene on a thin ferromagnetic metal film.

What is claimed is: 
     
       1. Magnetic recording media comprising a nonmagnetic support having thereon in sequence a ferromagnetic metal film magnetic layer having a thickness of from 0.02 to 2 μm and a protective layer comprising from 1 to 50 mg/m 2  of a polyoxyhexafluoropropylene comprising a chain of --(CF 2  CF 2  CF 2  --O)-- units and being terminally modified with a polar terminal group and having a main chain of linear structure; and wherein the terminal modifying group of the terminally modified polyoxyhexafluoropropylene is selected from the group consisting of --COOH, --OH, --SH, --COOCH 3  and --CONHR, where R is a hydrocarbon group having 1 to 22 carbon atoms.   
     
     
       2. Magnetic recording media as claimed in claim 1, wherein the terminal modified polyoxyhexafluoropropylene is coated in an amount of from 5 to 20 mg/m 2 . 
     
     
       3. Magnetic recording media as claimed in claim 1, wherein the ferromagnetic metal film magnetic layer has a thickness of from 0.05 to 0.4 μm. 
     
     
       4. Magnetic recording media as claimed in claim 1, wherein the surface of the ferromagnetic metal film magnetic layer has protrusions of a height from 10 to 1,000 Å and a size in diameter from 50 to 1,000 nm and a density of from 10 4  and 10 8  /mm 2 .